Bendiocarbamate toxicity in the chick embryo.

Carbamate pesticides generally possess low toxicity for warm-blooded vertebrates, but developmental data are scarce. We have therefore evaluated embryotoxicity of choline esterase inhibitor bendiocarbamate in the chick embryo. The pesticide was dissolved in 5% acetone in distilled water and a volume of 200 microl was administered over the embryo through membrana papyracea on embryonic days 2, 3, 4, 5, and 10.

[Host immune response in mammals to Encephalitozoon cuniculi infection].

The immunity system status of an individual plays the key role in regulation of opportune infection. In the fight against the intracellular parasites several non-specific as well as specific immunity mechanisms are applied. The dominant role in response to infection caused by the representatives of genus Encephalitozoon plays the cell-mediated immune response.

Immune response in mice infected by Encephalitozoon cuniculi and suppressed by dexamethasone.

Several indicators of immune response were observed in immunocompetent mice of the ICR line and those suppressed by dexamethasone upon their experimental infection with the microsporidia of Encephalitozoon cuniculi. The mice were infected by one-shot intraperitoneal administration of 5 x 10(7) pathogenic spores. On Days 7, 14, 28 and 42 after infection, peripheral blood leukocyte phagocytic activity was determined and compared, including phagocytic index and the blastogenic response in spleen cells to mitogenic activation by concanavalin A and phytohaemagglutinin.

Bovine leukemia virus-induced clinical signs and morphological changes of encephalitozoonosis in rabbits.

Fourteen three-month-old rabbits spontaneously-infected with the microsporidium Encephalitozoon cuniculi Levaditi, Nicolau et Schoen, 1923 were inoculated intravenously with lymphocytes (Ly) from seropositive bovine leukemia virus infected cattle (Ly/BLV) or with fetal lamb kidney cells infected with bovine fetal leukemia (FLK/BLV). Thirteen rabbits were seropositive to BLV at least for a period of three months. Six rabbits died of pulmonary lesions.

[The recovery and rearing of gnotobiotic lambs and their use in veterinary medicine].

Our own innovated method of the hysterectomy recovery of gnotobiotic lambs, modified equipment for gnotobiote rearing, management and tending techniques were tested in this study. A hysterectomy hood (Fig. 1) was made from plexiglass and it fully met the requirements for simple and rapid handling.

[Occurrence of viral particles of avian sarcoma viruses in sarcoma tissue].

An electron-microscopic examination was performed of chicken fibrosarcoma caused by avian sarcoma virus (ASV), strain B 77, to investigate virus budding and release through the cytoplasmic membrane. The virus particles of type C- were 90-100 nm in size, the electron-optically denser nucleoids being clearly differentiated from the outer membrane.

[Testing the susceptibility of cultured cells to infection with bovine leukemia virus].

Different cell cultures were studied for their susceptibility to bovine leucosis virus infection. Syncytial assay was used for this study. The FLS/BLV+ cell line served as virus source.

[Induction of cysts in adult rats by means of sodium nitrite after infection with avian sarcoma virus].

Trials were conducted to study the possible effect of sodium nitrite administered in drinking water as exerted upon carcinogenesis induced by the sarcoma virus in the organisms of adult rats during a five-month period of observation. No clinical changes were observed in these rats during the test period. On the 125th day of age the rats were subjected to post-mortem examination.

[The effect of sodium nitrite on rats infected with avian sarcoma virus].

A potential effect of sodium nitrite was studied as exerted on carcinogenesis elicited by the avian sarcoma virus in the body of rats. In the case of the infection of the rats with indefective avian sarcoma virus B77 (Bratislava strain; ID50 10-25/0.1 ml) and i.

[Transmission of Marek's disease to wild feathered game].

The following wild feathered game were tested from 6 to 12 months of age: common pheasant (Phasianus colchicus), common gray partridge (Perdix perdix), European quail (Coturnix coturnix), and Greek partridge (Alectoris graeca). Only pheasant was found to be susceptible to infection with a virulent virus of Marek's disease. In this bird the first clinical symptoms of the disease (nervous changes) were observed in 28 days from infection.

[Testing of poultry for susceptibility to sarcoma viruses in the C subgroup].

Experiments were performed to test the conventional chickens of the Ross I and Tetra-B broiler hybrid and the Shaver Starcross 288 and Slovgal laying hybrid for their susceptibility to the poultry sarcoma virus of subgroup C (B77). The chickens were inoculated six days from hatching and the first sarcomata began to appear at the inoculation spot on the fourth day. The first deaths were observed on the eighth day from inoculation, and the necropsy revealed frequent metastases.

[Immunological aspects of Marek's disease in chickens with maternal antibodies].

The dynamics of the production of immunoprecipitation antibodies to Marek's disease virus was studied in the serum of chickens with maternal antibodies in relation to the occurrence of the immunoprecipitation antigens of Marek's disease virus in feather follicles. One-day-old chickens were infected by the contact method with Marek's disease virus. The first occurrence of immunoprecipitation antigen was detected on the 14th day after infection and this occurrence persisted throughout the experiment, i.

[Testing the immunogenicity of the dermal antigen in Marek's disease virus].

An experiment was performed to study the immunogenicity of the dermal antigen of Marek's disease virus, extracted from the skin of 30-day-old chickens, infected with Marek's disease virus on the first day of life. Three kinds of samples were tested: (1) dermal antigen centrifuged at 10 000 g per 0.5 h, (2) dermal antigen centrifugated at 10 000 g per 0.

Pathogenesis of Marek's disease in chickens with maternal antibody.

Histopathological lesions were studied in chickens with maternal antibody against MD virus at 14-day intervals after their exposure by contact to HPRS-16 of MD virus in the first-day of life. The first lesions occured 14 days after infection in the liver, kidney, heart, brain and the sciatic nerves. Relatively, the most expressive changes were observed between 56th and 70th day after infection.

Immunization against Marek's disease using Marek's disease virus-specific antigens free from infectious virus.

Immunity against Marek's disease was conferred by the use of non-infectious materials extracted with non-ionic detergents from cells infected with the attenuated strain of Marek's disease virus (MDV). Antibody-free Rhode Island Red chicks were inoculated at 1 week of age with cell extracts emulsified in Freund's complete adjuvant and were given a second inoculation 1 week later without adjuvant. Protection against natural infection was obtained in groups inoculated with both soluble (not sedimented at 100,000 times g/2h) and insoluble antigens present in Nonidet P40 (NP40) extract, but only with the insoluble fraction of deoxycholate extract.